High Tunnel Melon and Watermelon Production

Whiteflies

Figure 20Whiteflies are late-season pests of high tunnel melons.

Greenhouse whitefly (Trialeurodes vaporariorum (Westwood)) is the most common whitefly species that can infest high tunnel melons and watermelons. Whiteflies are small (1/16 inch long), soft-bodied insects with wings covered with white, powdery wax. Whiteflies damage plants by sucking the sap and transmitting harmful viruses. Much like aphids, they excrete honeydew, which develops into sooty mold on the vines and fruit. In the central Midwest, whiteflies can appear within the high tunnel in late summer. Scout plants regularly, and check the underside of the leaves of new foliage for whitefly adults (Figure 20). Yellow sticky traps are useful in detecting whitefly population levels in the high tunnel. Natural enemies of whitefly include a parasitic wasp (Encarsio formosa), and Delphastus beetles (Delphastus catalinae). Several biological and soft pesticides are labeled for control of whitefly.